Fluid couplings known as “dry-break” couplings, such as the type commonly found on the end of flexible hoses often use ball valves. In one prior art example, a separate coupling body for each ball valve holds the ball valve in position which are joined together and held by a locking mechanism then, the ball valves are opened by the sequential rotation of two levers 90 degrees. One ball valve is convex while the second ball valve is concave in one section so that the two ball valves can be nested together to and then can be rotated to either a closed or open position. Closing the ball valves before disconnecting the coupling provides low spillage of the transported fluid. When the coupling bodies are joined together, each ball valve is rotated to a position which permits flow. Before the couplings are separated, each ball valve is rotated to a closed position and the coupling bodies are separated where each ball valve seals a respective coupling body. A concave ball valve and a convex ball valves are used which are interfit together when the coupling bodies are connected so that a minimum volume of fluid is lost when the ball valves are closed and the couplings are separated.
One improvement in ball valve design has been a semi-spherical depression in one ball valve with the other ball valve resting in the depression. This is known as a concave/convex ball valve design. This provides for minimal fluid spillage when the couplings are separated after the conveyance of fluids. One prior art handle or lever design prohibits incorrect sequencing of the ball valves during opening and closing using specially shaped cams formed on the handles. Another prior art feature is a interlocking mechanism to hold the coupling bodies together where a flange is formed on one of the coupling bodies that engages extensions on the second coupling body and a locking pin is activated by one of the handles to prevent disconnection of the coupling bodies once the ball valves are rotated towards an opening position.
In U.S. Pat. No. 5,402,825 to McCracken, a ball valve coupling is disclosed where the ball valves are flattened to provide a sealed fluid path between them. During the time that the coupling is being disconnected, one of the ball valves is axially displaced by a spring thereby allowing the ball valves to be rotated to a closed position. Also disclosed is a latch mechanism which prevents the coupling bodies from being disconnected as long as the ball valves are not in a fully closed position.
In U.S. Pat. No. 5,488,972 to McCracken et al., a ball valve coupling having coupling bodies that are joined and then locked together and the ball valves opened using two handles is disclosed. The handles have geometries that consist of convex and a concave cam portions that interact to prevent the rotation of the second handle until the first handle has been rotated into position. One ball valve includes flat surfaces on the ball and a retainer with flats that correspond to the flats on the ball valve. This feature keeps the ball valve on centerline and allows valve actuation without damage to either ball valve.